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serial: amba-pl011: Fix RX stall when DMA is used

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Function pl011_throttle_rx() calls pl011_stop_rx() to disable RX, which
also disables the RX DMA by clearing the RXDMAE bit of the DMACR
register. However, to properly unthrottle RX when DMA is used, the
function pl011_unthrottle_rx() is expected to set the RXDMAE bit of
the DMACR register, which it currently lacks. This causes RX to stall
after the throttle API is called.

Set RXDMAE bit in the DMACR register while unthrottling RX if RX DMA is
used.

Fixes: 211565b100 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle")
Cc: stable@vger.kernel.org
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20241113092629.60226-1-kkartik@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Kartik Rajput 2024-11-13 14:56:29 +05:30 committed by Greg Kroah-Hartman
parent 635a9fca54
commit 2bcacc1c87
1 changed files with 5 additions and 0 deletions
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5
drivers/tty/serial/amba-pl011.c
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@ -1819,6 +1819,11 @@ static void pl011_unthrottle_rx(struct uart_port *port)
pl011_write(uap->im, uap, REG_IMSC);
if (uap->using_rx_dma) {
uap->dmacr |= UART011_RXDMAE;
pl011_write(uap->dmacr, uap, REG_DMACR);
}
uart_port_unlock_irqrestore(&uap->port, flags);
}